Method of polishing.



UNITED STATES PATENT oEEIoE.

PET'EB'FIREMA'N, OF WASHINGTON, DISTRICT OF COLUMBIA;

METHOD OF POLISHING.

Specification of Letters Patent.

Patented Oct. 17, 1911.

Ho Drawing. Original application filed October 31, 1907, Serial No. 400,004. Divided and this application filed March 16, 1908, Serial No, 421,376. Renewed March 6, 1911. Serial No. 6L2,717.

l'b all whom it may concern:

Be it known that/I, PETER FIREMAN, a

. citizen of the United States, residing at \Vashington, District of Columbia, have invented certain new and useful Improvements in Methods of Polishing; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

Myinvention relates to the production of a high polish upon appropriate surfaces, and particularly upon surfaces of glass (as,

for instance, optical lenses), and upon oer tam metals to which a characteristic luster is simultaneously imparted, as, for instance, gold and platinum.

In carrying out my invention, I avail myself of the discovery made by me that the most finely divided chemically precipitated black magnetic ferro-ferric oxid, although vof .so fine a textureas to readily yield an impalpable powder, is, under certain conditions, capable of effectively polishing surfaces of the hardness of glass, and with a celerity and efficiency superior to that of certain oX'ids of iron found in nature, which, on pulverization, yield a powder decidedly rough to the touch and which are widely used in lens polishing on a large scale and for similar applications. In other words, I have found that precipitated ferro-ferric oxid,notwithst nding its impalpable fineness, develops an unexpected cut-ting power of such a uniform and regulable character that it may be relied upon with certainty for the production of the best standard effects, when applied under conditions of use which I have ascertained by extensive experimenta tion. The importance of this discovery will be the more apparent when itis remembered that polishing with the more or less rough powders scratches are not infrequently produced which prolong the polishing. operation even in the hands of the most skilful operators, and which sometimes are apparent in the finished article despite the effort made to entirely remove them. This difficulty is entirely obviated by the employment of the precipitated black, magnetic ferro ferric oxid in accordance with my invention.

In carrying out my invention for thewere permitted to become too dry.

the precipitated ferroferrio oxidinto eonditlon appropriate for use. Mixed with Water 1n the form of a paste, theprecipitated ferro-ferric oxid will cake on losing water,

and, if, in this. condition, it is rubbed against glass, it will produce deep scratches.

For a time, this seemed ,to be acircuinstancefatal to the successful employment, of the precipitated. ferro-ferric oxid as a glass olisher. Further experimentation, however, developed the fact that if the paste, before caking, is inserted between the polisher, which is lined with thick felt, and the lens embedded in the pitch which covers the block, the friction incident to the rubbing of the polisher against the lens, raises the temperature sufficiently to gradually evaporate a portion of the water of the layer of paste, causing the paste to gradually approach the caky condition. Thereupon, it develops its cutting power, without scratching, which would take place if it On theother hand, a certain "thickness or body of the paste must be maintained, if polishing at all is to take place, and I have ascer-.

tained that there is a practical range of eflective polishing action between the point at which the paste becomes sufficiently dry to dev Io p the quick cutting action, and that at which it is so dry as to threaten damage by scratching and that this range is sufficiently Wide to insure the uniform production of finished articles in a highly polished condition devoid of scratches. The operator quickly ascertains the proper consistency of the partially caked paste to produce the best results. Before the cutting power of the precipitated ferro-ferric oxid was ascertained, it seemed incomprehensible that this impalpable powder should not only do as effective polishing as the much rougher mathe mixture say ten pounds of the precipitated ferro-ferric magnetic oxid to five galions of water, although I do not restrict myself to these proportions. The paste mixture is to be stirred thoroughly at the time of application to the lens, and is preferably applied by means of a brush. The feit finally becomes saturated with the paste and is color imparted byjewelers rouge.

. volve, alternately,

' striking and characteristic iar to itself alone, in the polishlng of metals.

To gold it imparts an admirable rich dark luster, in contradistinction to the lighter Soalso,

to platinum, it gives a luster particularly acceptable to the eye, and which, so far as. I

am aware, is not produced by theuse of.

other polishing agents. In the polishing of metals, the precipitated magnetic ferro-ferric oxid is best used in the form of sticks, in which certain waxes or stearic acid, with fats are used as binding'material, and, in this form, it is also Well adapted for polishing hard rubber, mother of pearl, and the like." In compounding such polishing sticks, I may convenlently use as the ingre- 36 dients thereof,,say "100 pounds of the precipitated magnetic ferro-ferric oxid to 17 pounds of stearic acid (stearin) and 3 pounds of beef tallow, the stearic acid and talloW being first melted and the precipitated magnetic ferro-ferric oxid being then thoroughly and uniformly incorporated in it by vigorous stirring. The addition of tallow tends to soften the stick and increase the cutting power of the compound. If desired, I may add a small quantity of rouge to the composition, to vary the luster of tie finished article.

I do not claim herein the polishing a ent itself, consisting of a suitable vehicle an an abrading material whose principal constituent is precipitated ferro-ferric oxid, for the reason that the same is claimed in my copending application, S. N. 400,004, 'filed Oct. 3]., 1907, of which the present app1ication is a division. I

What I claim is 2- The method of. polishing, which consists in mixing precipitated magnetic ferro-ferric oxid witha liquid to form a paste, applying the paste between the polisher and the article tobe polished, causing a portion ofthe liquid to gradually evaporate, by friction,

and maintaining the precipitated. magnetic ferro-ferric oxid, during the polishing operation, in a condition intermediate between its initial pastiness and such dryness as would scratch the article operated upon; substantially as described.

In testimony whereof I afiix my signature, in presence of two witnesses.

PETER FIREMAN. \Vitnesses Jonu Cl PENNIE, LAURA B. PENFIELD. 

